Gas turbine exhaust diffuser, strut assembly, and trailing member for strut of gas turbine exhaust diffuser
The trailing member design with a tapering cross-section and stress relief slots addresses the cracking issues in gas turbine exhaust diffusers by reducing mechanical stress and improving structural integrity, thus enhancing reliability and reducing maintenance needs.
Patent Information
- Application Number
- JP2024199583
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-01
- Filing Date
- 2024-11-15
- Publication Date
- 2025-06-24
AI Technical Summary
The existing strut designs in gas turbine exhaust diffusers are prone to cracking due to complex factors such as temperature gradients, vibration-induced mechanical stresses, and poor weld seam intersections, necessitating frequent inspections and maintenance.
A trailing member for a strut in a gas turbine exhaust diffuser is designed with a tapering cross-section and stress relief slots in the side walls, allowing for deformation and reducing stress concentrations, thereby preventing cracking.
The design effectively reduces mechanical stress and the risk of cracking, improving the structural integrity and reducing the need for frequent maintenance, while maintaining aerodynamic efficiency.
Smart Images
Figure 2025093874000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a trailing member of a strut of a gas turbine exhaust diffuser as recited in the claims. The present disclosure further relates to a strut assembly including the trailing member and a gas turbine exhaust diffuser including the strut assembly.
Background Art
[0002] In a gas turbine exhaust diffuser, an inner diffuser barrel is suspended by struts within an outer diffuser barrel. The inner barrel may include, for example, a rear bearing of a gas turbine rotor. Exhaust gas flows through the annular flow path thus formed, and the exhaust gas may reach temperatures significantly exceeding 500°C, and when the output of the gas turbine changes, the temperature may be subject to relatively rapid changes.
[0003] In certain gas turbines, the strut may actually be a strut assembly that includes an upstream strut body and a downstream trailing member. To achieve an aerodynamic shape, the trailing member forms a trailing edge and may also be referred to as a trailing edge member. The strut body is attached (e.g., most commonly by a welded connection) to inner and outer diffuser barrels, but in certain known diffusers, the radially outer end of the trailing member is not fixed to the outer diffuser barrel. A flow shield is provided and attached to the outer diffuser barrel. This flow shield is essentially a sheet metal skirt that extends around a portion of the outer periphery of the downstream portion of the trailing member, including the downstream end of the trailing member, and terminates in at least an essentially co-planar (in known embodiments, the upstream side) plane with the seam between the strut body and the trailing member. The flow shield reduces the intake of hot combustion gases into the gap between the radially outer end of the trailing member and the outer diffuser barrel and suppresses the amplitude of vibration of the radially outer end of the trailing member. However, cracks may be observed due to complex factors in the vicinity of where the strut body and the flow shield are attached to the outer barrel, such as at the intersections of several weld seams, the interconnecting parts of several components, temperature gradients over time, and vibration-induced mechanical alternating stresses that typically occur in the exhaust diffuser of a gas turbine engine. Therefore, frequent inspections and maintenance are required. A solution or at least an improvement in the strut design and / or the strut-barrel connection is desired. SUMMARY OF THE INVENTION
[0004] The object of the present disclosure is to propose an apparatus of the type described at the beginning. In a more specific aspect, a technical improvement is provided. In a still more specific aspect of the technology proposed in the present application, although not limited, it alleviates or avoids problems in the technical field, including the above-mentioned problems.
[0005] This is achieved by the technology described in claim 1.
[0006] Specifically, the present disclosure relates to a trailing member for a strut of a gas turbine exhaust diffuser, the trailing member comprising an upstream side, a downstream end spaced from the upstream side in the downstream direction, and two side walls extending from the upstream side to the downstream end, the distance between the two side walls decreasing along the direction from the upstream side to the downstream end such that the cross-section of the trailing member tapers from the upstream side to the downstream end, the longitudinal range of the trailing member extending between a first longitudinal end of the trailing member and a second longitudinal end of the trailing member along the upstream side of the trailing member, a first edge of each side wall being disposed in proximity to the first longitudinal end of the trailing member, and a stress relief slot being provided in at least one of the first and second side walls and opening at the first edge of that side wall.
[0007] Also provided are a strut of a gas turbine exhaust diffuser having the trailing member and a gas turbine exhaust diffuser having the strut.
[0008] Other effects and advantages of the present disclosure will become apparent in light of the following disclosure, whether or not explicitly stated.
[0009] Disclosed is a trailing member for a strut of a gas turbine exhaust diffuser. The trailing member extends from an upstream side (in a more specific embodiment, an upstream surface) in the downstream direction to a downstream end. In many embodiments, the downstream end may form a trailing edge. Thus, in many embodiments, the trailing member may also be referred to as a trailing edge member. In many of these embodiments, the trailing member may provide the trailing edge of the strut assembly. The two side walls extend from the upstream side to the downstream end, and the distance between the two side walls decreases along the direction from the upstream side to the downstream end such that the cross-section of the trailing member tapers from the upstream side to the downstream end. More specifically, in various embodiments, the two side walls intersect at the trailing edge of the trailing member.
[0010] The longitudinal range of the trailing member extends between the first longitudinal end and the second longitudinal end of the trailing member along the upstream side of the trailing member. More specifically, the trailing member is for attachment to an exhaust diffuser as part of a strut assembly where the first longitudinal end is close to or adjacent to the outer (i.e., radially outer) diffuser barrel and the second longitudinal end is close to or adjacent to the inner (i.e., radially inner) diffuser barrel. Thus, the first longitudinal end of the trailing member can be referred to as the radially outer longitudinal end of the trailing member, and the second longitudinal end of the trailing member can be referred to as the radially inner longitudinal end of the trailing member. The first (in one aspect, radially outer) edge of each side wall is disposed close to the first longitudinal end of the trailing member.
[0011] More specifically, the first edge of each side wall is disposed at or defines the first longitudinal end of the trailing member. Stress relief slots are provided in at least one of the first and second side walls and open at the first edge of each side wall. In a more specific embodiment, stress relief slots or one or more stress relief slots are provided in both the first and second side walls and open at the first edge of each side wall. In use, the stress relief slots allow the trailing member to deform to some extent at the first longitudinal end close to or adjacent to the outer barrel, reducing stress and helping to prevent cracking.
[0012] In the present disclosure, the use of the indefinite article does not mean singular and does not exclude the presence of a plurality of such members or features, and should be construed to mean "one or more" or "one or a plurality of".
[0013] In a more specific embodiment, one or more stress relief slots are provided in at least one of the first and second sidewalls and open at a first edge of the sidewall, and a round stress relief hole is terminated when starting from an opening end at the first edge of the sidewall. Accordingly, notching at the ends of the stress relief slots and the accompanying stress concentration are avoided.
[0014] In a plurality of embodiments, the trailing member includes a cover plate between the first sidewall and the second sidewall adjacent to a first longitudinal end of the trailing member, and the cover plate extends across one or more stress relief slots provided in at least one of the first and second sidewalls. The cover plate is provided with stress relief slots and opens at an edge of the cover plate adjacent to one or more stress relief slots in at least one of the first and second sidewalls. In this way, the cover plate does not prevent the deformation of the first and / or second sidewalls enabled by the stress relief slots of the respective sidewalls. Of course, the stress relief slots in the cover plate can terminate in round stress relief holes when starting from an opening end at the edge of the cover plate.
[0015] Furthermore, a U-shaped notch may be provided in the cover plate provided between the first sidewall and the second sidewall adjacent to the first longitudinal end of the trailing member, close to the upstream end of the cover plate.
[0016] The cover plate may be welded to the first and second sidewalls. Along a distance adjacent to the upstream edge of the cover plate, the welding seam may be omitted. Then, a gap is formed between the cover plate and each of the first and second sidewalls. In this way, in the region where the welding seam is omitted, movement between the sidewall and the cover plate becomes possible, and stress concentration due to differences in thermal expansion and the like is avoided.
[0017] The first edge of each of the first and second sidewalls may be formed convexly when viewed in a side view with respect to the surface of each sidewall. More specifically, the first edge may include a kink in the side view, and even more specifically, may include one or more linear edge segments that terminate at the kink in the side view. In other embodiments, the kink may be provided between two linear edge segments in the side view. This design enables the first longitudinal end of the trailing member to be specifically adapted to the outer barrel and can be suitably adapted to the configuration and dimensions of the gap between the first longitudinal end of the trailing member and the outer barrel. The presence and width of the gap between the first longitudinal end of the trailing member and the outer barrel can be varied as it progresses from the upstream side of the trailing member to the downstream end of the trailing member, and can be suitably adapted to the need to reduce mechanical stress formation.
[0018] Furthermore, in an embodiment, each of the first and second sidewalls includes a convex corner, and one of the one or more stress relief slots may open at the convex corner. This embodiment is particularly useful for reducing stress that may occur between the more upstream and more downstream sections of the first and second sidewalls when connecting (especially by welding) the upstream portions of the first and second sidewalls (proximate to the upstream end of the trailing member) to the outer barrel.
[0019] Furthermore, the first edge of each sidewall may be recessed and have a concave portion adjacent to the upstream side of the trailing member. This means that when the trailing member is installed in the diffuser, the outermost upstream radial corner of the trailing member forms a window and does not interfere with the welding seam that attaches the strut body to the outer barrel of the diffuser. Furthermore, the window thus provided facilitates inspection by simple optical inspection of the entire welding seam and connection.
[0020] In a more specific embodiment, the concave portion may include a concave corner, and the stress relief slot opens at the concave corner.
[0021] The distance between the upstream side of the trailing member and the downstream end of the trailing member may be decreased, particularly linearly, from the first longitudinal end of the trailing member to the second longitudinal end of the trailing member. That is, the upstream-downstream extent of the trailing member decreases from the first longitudinal end of the trailing member to the second longitudinal end of the trailing member, and in a more specific embodiment, the trailing member may be wedge-shaped. When the trailing member is used as intended (i.e., as the downstream member of the strut assembly inside the diffuser), the first longitudinal end of the trailing member is positioned proximate or adjacent to the outer barrel (i.e., radially outward), and the second longitudinal end of the trailing member is positioned proximate or adjacent to the inner barrel (i.e., radially inward), and the length of the strut assembly in the upstream-downstream direction is smaller at the radially inward position than at the radially outward position. This may provide an aerodynamic advantage.
[0022] The stress relief slot may be provided proximate to the second (i.e., when used radially inward as intended) longitudinal end of the trailing member. The stress relief slot opens at the downstream end of the trailing member.
[0023] Each stress relief slot described herein terminates in a rounded stress relief hole starting from the open end. As described above, this can avoid inconvenient stress concentration at the ends of each stress relief slot.
[0024] In another aspect, a strut assembly is disclosed. The strut assembly includes a strut body and a trailing member of the type described above. The strut body extends in a longitudinal direction between a first longitudinal end and a second longitudinal end. The strut body has an upstream side and a downstream side. The trailing member is attached to the downstream side of the strut body and extends longitudinally along the downstream side of the strut body to form a trailing section of the strut assembly. The upstream side of the trailing member is disposed adjacent to the downstream side of the strut body. The first longitudinal end of the trailing member is disposed adjacent to the first longitudinal end of the strut body, and the second longitudinal end of the trailing member is disposed proximate to the second longitudinal end of the strut body. In this way, the first longitudinal end of the strut body is planned or adapted and configured to be disposed radially outward when installed in the diffuser, and the second longitudinal end is planned to be disposed radially inward. The upstream end of the strut body may be convexly rounded in a cross-sectional view of the strut body, particularly to form a leading edge of the aerodynamic shape of the strut assembly, and the trailing member forms a trailing edge of the strut assembly.
[0025] In this regard, the first (i.e., radially outer in the intended use state) longitudinal end of the trailing member is disposed adjacent to the first longitudinal end of the strut body, and the trailing member terminates in front of the second longitudinal end of the strut body as measured along the downstream side of the strut body when measured along the upstream side of the trailing member in the direction from the first longitudinal end of the trailing member to the second longitudinal end of the trailing member. As described above, the first longitudinal end of the trailing member and the first longitudinal end of the strut body are provided so as to extend radially inward from the outer barrel of the diffuser adjacent to the outer barrel, and the second longitudinal end of the trailing member and the second longitudinal end of the strut body are provided so as to extend radially outward from the inner barrel of the diffuser adjacent to the inner barrel. Along the radially inner section of the strut assembly, the downstream end of the strut body is not covered by the trailing member, which may adversely affect aerodynamics. As an advantage, the adverse effect on the structural integrity due to thermal stress caused by the interference between the strut body, the trailing member, and the inner barrel of the diffuser is avoided. The section of the strut assembly where the downstream end of the strut body is not covered by the trailing member is relatively small, and since this section is in the radially inner region, the portion of the total mass flow rate affected by the aerodynamic defect is relatively small, and the gain by eliminating the amplification of potential mechanical stress may exceed the aerodynamic adverse effect.
[0026] In yet another aspect, a diffuser of a turbo engine (e.g., but not limited to, a gas turbine exhaust diffuser) is disclosed, which comprises an inner barrel and an outer barrel, defining a flow path therebetween, and further comprises one or more strut assemblies of the type described above extending between the inner barrel and the outer barrel. The first longitudinal end of the strut body is attached (in particular, welded) to the outer barrel, and the second longitudinal end of the strut body is attached (in particular, welded) to the inner barrel. Further, a flow shield is provided and attached (in particular, welded) to the outer barrel. The flow shield extends along a part of the outer periphery of the downstream portion of the trailing member adjacent to the first longitudinal end of the downstream end of the trailing member, including those extending around the downstream end of the trailing member. The upstream edge of the flow shield is spaced from the downstream side of the strut body in the downstream direction of the diffuser. The flow shield, on the one hand, suppresses excessive intake of gas (e.g., combustion gas) between it and the longitudinal end provided radially outside the trailing member, and on the other hand, serves to suppress excessive mechanical vibration of the trailing member.
[0027] In an embodiment, a gap may be provided between the trailing member and the outer barrel along the downstream section of the first longitudinal end of the trailing member including the downstream end of the trailing member, and the first and second side walls of the trailing member are welded to the outer barrel along at least a part of the upstream section of the trailing member. Stress relief slots provided in at least one of the first and second side walls may open at the edges of the side walls of the non-welded portion adjacent to or in contact with the downstream end of the weld seam.
[0028] As used herein, the term "proximate", particularly when used with respect to an end or side of a member, means that one end or side of the member is closer to a particular second member or a mark of the member than another end or side. In particular, a member or a mark of a member described as being proximate to a second member or a mark of the member may, in a more specific embodiment, be directly adjacent to or in contact with the second member or a mark of the member.
[0029] The features and embodiments disclosed above may be combined with each other. Other embodiments can be conceived within the technical scope described in the scope of the present disclosure and the claims, and they will be obvious to those skilled in the art in light of the present disclosure.
[0030] Hereinafter, the present disclosure technology will be described more specifically by a predetermined exemplary embodiment shown in the accompanying drawings.
Brief Description of the Drawings
[0031]
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
[0032] Note that the drawings are schematic diagrams, and in order to facilitate understanding and illustration, unnecessary details may be removed. Also, what is shown in the drawings is a predetermined exemplary embodiment, and embodiments not shown in the drawings may also fall within the technical scope described in the scope of the present disclosure and / or the claims.
Modes for Carrying Out the Invention
[0033] Figure 1 shows an exemplary strut assembly 2 within a diffuser of a turboengine (e.g., diffuser 1 in the exhaust section of a gas turbine engine). The diffuser 1 is generally defined as an annular portion (annulus) between an outer barrel 11 and an inner barrel 12. The inner barrel 12 can accommodate, for example, the rear bearing and other components of a gas turbine engine. A plurality of circumferentially arranged and radially extending strut assemblies, such as the strut assembly 2 shown in the figure, provide structural support between the outer barrel 11 and the inner barrel 12. The flow of combustion gases passes through the diffuser 1 as indicated by the arrows in Figure 1. The diffuser 1 serves to decelerate the gases from the expansion turbine and regain static pressure, which has a beneficial effect on efficiency. Therefore, it is desirable that a strut assembly such as the strut assembly 2 does not introduce excessive resistance to the flow of gases through the diffuser 1.
[0034] The strut assembly 2 comprises a strut body 3 and a trailing member 4. The strut body 3 may be cooled, for example, by supplying a flow of cooling air through the strut body 3. The flow of the coolant may be directed longitudinally through the strut body 3, which corresponds to a radial flow with respect to the diffuser 1.
[0035] In the exemplary embodiment shown in the figure, the strut body 3 includes two sections, an upstream section 3a and a downstream section 3b. However, this is not relevant to the present invention. In the configuration shown in the figure, the first (radially outer) longitudinal end of the strut body 3 is welded to the outer barrel 11, and the second (radially inner) longitudinal end of the strut body 3 is welded to the inner barrel 12. The strut body 3 thus provides structural support between the outer barrel 11 and the inner barrel 12.
[0036] The upstream side 31 of the strut body 3 is rounded in the cross-sectional view of the strut body 3 and aerodynamically forms the leading edge 21 of the strut assembly 2. The upstream side 41 of the trailing member 4 is attached to the downstream side 32 of the strut body 3 to together form the strut assembly 2. The downstream end 42 of the trailing member 4 forms the trailing edge 22 of the strut assembly 2. Therefore, the cross-sectional shape of the strut assembly 2 is substantially droplet-shaped. Also, as shown in the side view of FIG. 1, the trailing member 4 is substantially wedge-shaped. Therefore, the upstream-downstream range of the trailing member 4 increases toward the radially outer side.
[0037] The flow shield 5 is attached to the radially outer barrel 11 and extends along a part of the outer periphery of the downstream portion of the trailing member 4 adjacent to the radially outer end of the trailing member 4. This flow shield 5 is a skirt that extends in the vicinity of the connection portion of the downstream portion of the radially outer end of the trailing member 4. As will become apparent below, one function of the flow shield 5 may be to avoid excessive intake of combustion gas into the gap existing between the outer barrel 11 and the downstream section of the trailing member 4. In another aspect, the function of the flow shield 5 may be to damp the vibration of the cantilever downstream portion of the radially outer end of the trailing member 4.
[0038] FIG. 2 shows more details of the strut assembly 2 separated from the diffuser 1. The trailing member 4 includes two side walls 43, 44, and the side walls 43, 44 merge at the downstream end 42 of the trailing member 4 to together form the trailing edge 22. The side walls 43 and 44 may be, for example, in the cross-section of a single monolithic member of sheet metal in one embodiment, but in other embodiments, they may be separate members joined to each other, for example, along the trailing edge 42. In this figure, only the edge 441 of the side wall 44 is visible, but the shape and position of the side wall 44 will be apparent to those skilled in the art. The first edge 431 of the first side wall 43 and the first edge 441 of the second side wall 44 are arranged in the vicinity of or form the first longitudinal end of the trailing member 4 and are provided as the longitudinally outer end of the trailing member 4 in the radially outer side.
[0039] The cover plate 49 is provided between the first side wall 43 and the second side wall 44, adjacent to the first longitudinal end of the trailing member 4 or between the first edges 431, 441 of the side walls 43, 44, respectively. The cover plate 49 closes the trailing member 4, which may be a hollow member defined by the first and second side walls 43, 44 and the upstream end wall of the trailing member 4 and the first longitudinal end 41 of the trailing member 4. Further, as is apparent, the first longitudinal end 41 of the trailing member 4 is recessed by a recess 46 adjacent to the upstream side 41 of the trailing member 4 and / or adjacent to the downstream side 32 of the strut body 3. The stress relief slot 45 is provided adjacent to the second longitudinal end on the opposite side of the trailing member 4 to address stress concentration that may occur due to the intersection of the strut body 3, the trailing member 4, and the inner barrel 12.
[0040] FIG. 3 shows details of the first longitudinal end of the trailing member 4 together with the flow shield 5. The first edge 431 of the first side wall 43 of the trailing member 4 includes an upstream section 431a and a downstream section 431b. When viewed along the upstream-downstream direction, the downstream section 431b of the first edge 431 of the first side wall 43 is angled radially inward with respect to the upstream section 431a of the first edge 431 of the side wall 43, that is, toward the second longitudinal end of the trailing member 4. Similarly, the first edge 441 of the second side wall 44 of the trailing member 4 includes an upstream section 441a and a downstream section 441b. When viewed along the upstream-downstream direction, the downstream section 441b of the first edge 441 of the second side wall 44 is angled radially inward with respect to the upstream section 441a of the first edge 441 of the second side wall 44, that is, toward the second longitudinal end 441 of the trailing member 4. Thus, the first edges 431, 441 of each of the first and second side walls 43, 44 are formed in a convex shape when viewed in a side view of each side wall. In another aspect, it can be said that the first longitudinal end of the trailing member 4 is formed in a convex shape on either of the side walls 43, 44 in a side view.
[0041] The cover plate 49 also includes two sections 49a and 49b, and the downstream section 49b is angled radially inward of the trailing member 4 or toward the second longitudinal end with respect to the upstream section 49a of the cover plate 49 when viewed along the upstream-downstream direction. With this shape, the gap between the first longitudinal end of the trailing member 4 and the outer barrel 11 can be configured to be smaller in the upstream section of the first longitudinal end of the trailing member 4 than in the downstream section of the first longitudinal end of the trailing member 4.
[0042] As shown in FIG. 1, the flow shield 5 may be configured such that the upstream edge of the flow shield 5 is spaced downstream from the downstream side of the strut body 3 in the downstream direction of the exhaust diffuser 1. In this way, the welding seam for attaching the flow shield 5 to the outer barrel 11 and the welding seam for attaching the strut body 3 to the outer barrel 11 do not intersect.
[0043] A recess 46 adjacent to the upstream side 41 of the trailing member 4 is further provided at the first longitudinal end of the trailing member 4. This recess is formed by the first edges 431, 441 of the side walls 43, 44 being recessed on the upstream side 41 of the trailing member 4. The recesses of the first edges 431, 441 of each of the side walls 43 and 44 each include a concave corner. The stress relief slots 47, 48 of the side walls 43, 44 open at their respective concave corners. Each stress relief slot 47, 48 terminates in a rounded stress relief hole starting from the open end of the first edge 431, 441 of each side wall 43, 44, and only the stress relief hole 471 of the stress relief slot 47 is visible in this figure. The stress relief holes (e.g., 471) are sized and shaped to avoid the notch effect at the ends of their respective stress relief slots (e.g., 47).
[0044] The cover plate 49 extends across the stress relief slots 47, 48 of the side walls 43, 44. The cover plate 49 is provided with stress relief slots 491, 492 that open at the ends of the cover plate 49 adjacent to each of the stress relief slots 47, 48 adjacent to each of the side walls 43, 44. As is apparent from the figure, the stress relief slots 491, 492 of the cover plate 49 also terminate in round stress relief holes (not numbered). Since the upstream end 41 of the trailing member 4 is recessed from the downstream section of the trailing member 4, the welding seam (Figs. 1, 2) that joins the upstream edges of the side walls 43, 44 to the downstream side of the strut body 3 does not intersect the welding seam that attaches the strut body 3 to the outer barrel 11. Also, the cover plate 49 is welded and connected to the inside of each of the side walls 43, 44 in the cross-section on the downstream side of the stress relief slots 47, 48, 491, 492, creating a gap between the cover plate 49 and the inner surfaces of the side walls 43, 44 at the upstream end of the trailing member 4 while omitting the welding seam. When the trailing member 4 is installed as intended, no stress is applied between the cover plate 49 and the side walls 43, 44 of the adjacent strut body 3. The stress relief slots 47, 48, 491, 492 provided at the first longitudinal end of the trailing member 4 reduce mechanical stress and thus the risk of cracking, while avoiding intersecting welding seams. Also, the recess 46 facilitates the optical inspection of the connection between the strut body 3, the trailing member 4, and the outer barrel 11.
[0045] As shown in Fig. 3, the flow shield 5 is also provided with a stress relief slot 51 that opens at the free end of the flow shield 5. The stress relief slot 51 is basically in the shape of an anchor and terminates in a round stress relief hole.
[0046] Figure 4 shows the strut assembly 2 installed within the diffuser 1, which incorporates different embodiments of the trailing member 4. Basically, similar to the configuration shown in FIG. 1, the upstream side 41 of the trailing member 4 and the downstream side 32 of the strut body 3 are joined. Thereby, the trailing member 4 forms the trailing section of the strut assembly 2. Similar to the embodiments outlined with respect to FIGS. 1 - 3, the flow shield 5 is attached to the outer barrel 11 and extends along a part of the outer periphery of the downstream portion of the trailing member 4, adjacent to the radially outer end of the trailing member 4. The trailing member 4 is in a direction such that a gap 121 is provided between the second (radially inner) longitudinal end of the trailing member 4, the front end portion of the second longitudinal end of the strut body 3, and the inner barrel 12 from the first (radially outer) longitudinal end of the trailing member 4.
[0047] In this embodiment, since the second longitudinal end of the trailing member 4 is a freely cantilevered beam from the downstream side 32 of the strut body 3, rather than being fixed to the inner barrel 12 like the strut body 3, the second longitudinal end of the trailing member 4 has lower stress adjacent to the second longitudinal end of the trailing member 4 compared to the embodiments of FIGS. 1 - 3, and the stress relief slot 45 adjacent to the second longitudinal end of the trailing member 4 is omitted. As a disadvantage, the adjacent inner barrel 12 may impair aerodynamics. However, depending on the ratio of the diameter of the outer barrel 11 to the diameter of the inner barrel 12, the proportion affected by the total mass flow rate is small enough to ignore the aerodynamic disadvantage.
[0048] Figure 5 shows the details of the first longitudinal end of the trailing member 4 of FIG. 4, i.e., the longitudinal end on the radially outer side of the trailing member 4, which is adapted, configured, or required to be provided respectively. For enhancing visibility, the flow shield 5 is not shown. The first edges 431 and 441 include upstream sections 431a and 441a and downstream sections 431b and 441b. When viewed along the upstream-downstream direction, the downstream sections 431b and 441b are angled towards the second longitudinal end of the trailing member 4 with respect to the respective upstream sections 431a and 441a. Thus, the first edges 431, 441 of each of the first and second side walls 43, 44 are formed convexly in the side view of each side wall. In another aspect, it can be said that the first longitudinal end of the trailing member 4 is formed convexly on either of the side walls 43, 44 in the side view.
[0049] In the embodiment shown in the figure, the stress relief slots 47 and 48 open at the corners of the first edges 431 and 441 of the side walls 43 and 44 where the upstream sections 431a and 441a and the respective downstream sections 431b and 441b meet. The stress relief slots 47, 48 are inclined or angled with respect to the longitudinal extent of the trailing member 4 or radially when the trailing member 4 is installed as intended. The stress relief slots 47 and 48 extend below the upstream sections 431a and 441a of the first edges 431 and 441 of the side walls 43 and 44 when forming the openings at each edge. The inclination relaxes the stress particularly efficiently when the trailing member 4 is installed inside the diffuser 1. The stress relief slots 47 and 48 each terminate in rounded stress relief holes 471 and 481. The upstream edge of the cover plate 49 is positioned spaced apart from the upstream end 41 of the trailing member 4 and is positioned to open to the upstream side 41 adjacent to the first longitudinal end of the trailing member 4. Also, a U-shaped notch 495 is provided in the upstream edge of the cover plate 49. The notch 495 may have a shape other than U-shaped if desired.
[0050] FIG. 6 shows the configuration of FIG. 4 in a state where the flow shield 5 is absent. The radially outer end of the trailing member 4, which is the first upstream section, is welded to the outer barrel 11. Referring to FIG. 5, the upstream sections 431a, 441a of the first edges 431, 441 of the side walls 43, 44 are welded to the outer barrel 11. On the other hand, a gap 111 is provided between the outer barrel 11 and the downstream section of the first longitudinal end of the trailing member 4. Referring to FIG. 5, a gap 111 is provided between the downstream sections 431b, 441b of the first edges 431, 441 of the side walls 43, 44 and the barrel 11. Referring to FIG. 4, the gap 111 is normally covered by the flow shield 5. As can be easily concluded from the combined drawings of FIGS. 5 and 6, the stress relief slots 47 and 48 extend between the welded sections and the non-welded sections of the first edges 431 and 441 of the side walls 43 and 44. The stress relief slots 47 and 48 provide a certain degree of flexibility to the side walls 43 and 44 adjacent to the respective first edges 431 and 441, and can accommodate a certain degree of deformation without inducing excessive stress.
[0051] Although the disclosed technology has been described with reference to exemplary embodiments, these do not limit the technical scope described in the claims. The claims also include embodiments not explicitly described or disclosed in this application, and embodiments that deviate from the embodiments described in the exemplary forms for implementing the teachings of this disclosure are also included in the claims.
Description of Reference Numerals
[0052] 1 Gas turbine exhaust diffuser 2 Strut assembly 3 Strut body 4 Trailing member 11 Outer barrel 12 Inner barrel 31 Upstream end of the strut body 32 Downstream side of the strut body 41 Upstream side of the trailing member Downstream end of the trailing member 42 First side wall 43 Second side wall 44 Stress relief slot 47 Stress relief slot 48 Cover plate 49 First edge of the first side wall 431 First edge of the second side wall 441
Claims
1. A trailing member (4) for a strut (2) of a gas turbine exhaust diffuser (1), the trailing member having an upstream side (41), a downstream end (42) spaced apart from the upstream side (41) along a downstream direction, and two side walls (43, 44) extending from the upstream side to the downstream end, the distance between the two side walls decreasing along a direction from the upstream side to the downstream end such that a cross section of the trailing member (4) tapers from the upstream side (41) to the downstream end (42), A trailing member, the longitudinal extent of which extends along the upstream side of the trailing member between a first longitudinal end of the trailing member and a second longitudinal end of the trailing member, a first edge (431, 441) of each side wall being disposed adjacent to the first longitudinal end of the trailing member (4), and a stress relief slot (47, 48) is provided in at least one of the first and second of the two side walls (43, 44) and opens at the first edge (431, 441) of that side wall.
2. 2. The trailing member of claim 1, wherein the stress relief slot (47, 48) is provided in at least one of the first and second side walls (43, 44), opens at a first edge of the side wall, and terminates in a round stress relief hole (471, 481) when taken from the open end at the first edge of the side wall.
3. 3. A trailing member as claimed in claim 1 or claim 2, wherein the trailing member comprises a cover plate (49) between the first and second side walls adjacent a first longitudinal end of the trailing member, the cover plate (49) extending across one or more stress relief slots (47, 48) in at least one of the first and second side walls, and additional stress relief slots (491, 492) in the cover plate opening at an edge of the cover plate adjacent the stress relief slots (47, 48) in at least one of the first and second side walls.
4. 4. The trailing member of claim 1, wherein a cover plate (49) disposed between the first and second side walls adjacent the first longitudinal end of the trailing member includes a U-shaped cutout (495) disposed proximate an upstream end of the cover plate.
5. 5. A trailing member as claimed in claim 3 or claim 4, wherein the cover plate (49) is welded to the first and second side walls (43, 44) and the weld seam is omitted along a distance adjacent the upstream edge of the cover plate.
6. 6. A trailing member as claimed in any one of claims 1 to 5, wherein the first edge (431, 441) of each of the first and second side walls (43, 44) is formed convexly when viewed in a side view relative to the plane of the respective side wall.
7. 7. The trailing member of claim 1, wherein the first edge (431, 441) of each of the first and second side walls (43, 44) includes a convex corner, and one stress relief slot (47, 48) opens at the convex corner.
8. A trailing member according to any preceding claim, wherein a first edge (431, 441) of each side wall (43, 44) is recessed adjacent an upstream side of the trailing member to define a recess (46).
9. The trailing member of any one of claims 1 to 8, wherein the recess (46) includes a concave corner and the stress relief slots (47, 48) open into the concave corner.
10. 10. The trailing member of claim 1, wherein the distance between the upstream side (41) of the trailing member and the downstream end (42) of the trailing member decreases from the first longitudinal end of the trailing member to the second longitudinal end of the trailing member.
11. 11. A trailing member as claimed in any one of claims 1 to 10, further comprising an additional stress relief slot (45) disposed adjacent the second longitudinal end of the trailing member (4) and opening at the downstream end of the trailing member.
12. 12. A strut assembly (2) comprising a strut body (3) and a trailing member (4) according to any one of claims 1 to 11, wherein the strut body extends longitudinally between a first longitudinal end and a second longitudinal end, the strut body (3) having an upstream end (31) and a downstream side (32), the trailing member (4) is attached to the downstream side (32) of the strut body (3) and extends longitudinally along the downstream side (32) of the strut body to form a trailing section of the strut assembly (2), the upstream side (41) of the trailing member (4) being disposed adjacent the downstream side (32) of the strut body (3), a first longitudinal end of the trailing member (4) being disposed adjacent to the first longitudinal end of the strut body (3) and a second longitudinal end of the trailing member (4) being disposed adjacent to the second longitudinal end of the strut body (3).
13. 12. A strut assembly as claimed in claim 11, wherein the trailing member (4) terminates short of the second longitudinal end of the strut body (3) measured along the downstream side (32) of the strut body when measured along the upstream side (41) of the trailing member in a direction from the first longitudinal end of the trailing member to the second longitudinal end of the trailing member.
14. 14. A gas turbine exhaust diffuser (1) comprising an inner barrel (12) and an outer barrel (11) defining a flow path therebetween, the gas turbine exhaust diffuser comprising one or more strut assemblies according to claim 12 or claim 13 extending between the inner barrel and the outer barrel, a first longitudinal end of a strut body (3) attached to the outer barrel (11) and a second longitudinal end of the strut body (3) attached to the inner barrel (12), a flow shield (5) provided on and attached to the outer barrel (11), the flow shield (5) extending adjacent the first longitudinal end of the trailing member (4) along a portion of an outer periphery of a downstream portion of the trailing member including a downstream end (42) of the trailing member (4), an upstream edge of the flow shield being spaced from the downstream side (42) of the strut body (3) in a downstream direction of the turbo engine diffuser.
15. 15. The gas turbine exhaust diffuser of claim 14, wherein a gap (111) is provided between the trailing member (4) and the outer barrel (11) along a downstream section of the first longitudinal end of the trailing member including the downstream end of the trailing member, and the first and second sidewalls (43, 44) are welded connected to the outer barrel along at least a portion of the upstream section of the trailing member.